Only safe call allowed error when EditText is used to send string to firebase in android studio

I am new to Firebase. I have made a simple project which sends user strings to Realtime Database in Firebase. For input, I have used the EditText view. Here is my main activity. username is the id of EditText View

package com.example.firebase
import...

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding
    private lateinit var database: DatabaseReference
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        binding.Remote.setOnClickListener {


            val name = binding.username.text.toString() //Error on this line
            database = FirebaseDatabase.getInstance().getReference("Users")
            val User = User(name)
            database.child(name).setValue(User).addOnSuccessListener {
                binding.username.text.clear() //And This Line
                Toast.makeText(this,"Sucess", Toast.LENGTH_SHORT).show()
            }.addOnFailureListener {
                Toast.makeText(this,"Failed", Toast.LENGTH_SHORT).show()
            }
        }

After Building following error is shown on the commented line of code:

Only safe (?.) or non-null asserted (!!.) calls are allowed on a nullable receiver of type EditText.

It works fine if I direct enter a string instead of using EditText View. Can someone help me with this?